I have to agree. My experience's with Apple's in store Geniuses have been quite poor compared to phone support.
You missed out on this one then.
That was just the point I was making. The guy in that thread goes, "I spent 15 minutes going off on the store manager and got nowhere".
At any rate I hope the OP gets the screw replaced, I would just go to another store and approach the situation very nicely and calm.